In accordance with a rapid spread of information relevant apparatuses and communication apparatuses such as a personal computer, a video camera and a portable telephone in recent years, the development of a battery to be utilized as a power source thereof has been emphasized. The development of a high-output and high-capacity battery for an electric automobile or a hybrid automobile has been advanced also in the automobile industry. A lithium battery has been presently noticed from the viewpoint of a high energy density among various kinds of batteries.
Liquid electrolyte containing a flammable organic solvent is used for a presently commercialized lithium battery, so that the installation of a safety device for restraining temperature rise during a short circuit and the improvement in structure and material for preventing the short circuit are necessary therefor. On the contrary, a lithium battery all-solidified by replacing the liquid electrolyte with a solid electrolyte layer is conceived to intend the simplification of the safety device and be excellent in production cost and productivity for the reason that the flammable organic solvent is not used in the battery.
Also, a laminated bipolar battery, which allows a high energy density and a high output density, is noticed as the above-mentioned lithium battery for an electric automobile. The bipolar battery is such that a bipolar electrode, in which a cathode active material layer is formed on one plane of a current collector and an anode active material layer is formed on the other plane thereof, and an electrolyte are alternately laminated.
Here, the bipolar battery has a constitution such that the plural bipolar electrodes are laminated, so that the problem is that there is a possibility that a short circuit is caused by contact between the current collectors and contact between an electrode active material layer and the current collector in an uneven portion at the end of the bipolar electrode. Then, in Patent Literature 1, it is disclosed that an insulating part made of an insulating material is provided on the current collector in the periphery of the bipolar electrode, where the electrode active material layer is not formed.